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dozentrio
03-14-2007, 08:03 AM
I was reading about turbos -ages- ago(long before I'd even driven a car), probably on wikipedia or howstuffworks or something like that, but I remember that they said a problem with turbo's is turbolag, spool time, etc. We all know this of course, but what was interesting about it was that they said one way car companies attempted to deal with it was by putting a small turbo and a big turbo in series. So the exhaust goes through the small turbo, into the big turbo, and on to the cat or test pipe or whatever. Bonus is, the small turbo spools up right away giving you "instant" power, and then the big turbo spools giving you lots of power.

Soo, do you think it would be possible to do? a k04 and then a BT? Ignore the fact that it probably wouldn't fit for now, what kind of problems do you suppose it might cause? You'd need lots of oil/coolant lines, I suppose... 2 boost controllers? Weird tuning...

Anyway, I'm just throwing it out there.

nizmosx
03-14-2007, 08:47 AM
the setup is called sequential turbos, and i dont think it would be that great of an idea on our cars. To be honest its not worth it. One of the cars that come with this setup is a toyota supra turbo and when they do a bt upgrade they ditch the dual setup for 1 larger turbo. It can be efficient if setup right but on an a4 with the lack of room/ tuners/ and a big wallet. its a skip.

SurferForever
03-14-2007, 08:57 AM
how much smaller fo a turbo then a k03 could you find?

bOOOOstedAudi
03-14-2007, 09:02 AM
and besides our turbo range do not vary that much to need it. the smallest turbo for our car kits in at what 3k and the largest elim kicts in where 4 something.

bOOOOstedAudi
03-14-2007, 09:03 AM
and 1.8l 4 cyl does not help. i think it would have trouble pushing 2 turbos efficiently.

Nor_Cal_Driver
03-14-2007, 09:07 AM
Isn't the 2.7t setup in sequence?

ShawFM
03-14-2007, 09:18 AM
how much smaller fo a turbo then a k03 could you find?

My '82 CX500T was turbocharged. It had a tiny IHI turbo that let the bike make 80hp on a 70's era engine that would have normally made less than 40hp. It was a 500cc fuel injected V twin.

Picture of a CX500T (http://www.hftc.nl/TechniekGB.htm) not mine.

seank
03-14-2007, 09:20 AM
Isn't the 2.7t setup in sequence?

no they are the same size. and actually twin turbo supra's utilized the same sized turbos not different sizes, the difference being they were routed sequentially not in parallel.

dozentrio
03-14-2007, 09:22 AM
The 2.7 L engine in the S4 and (some?) A6 is twin-turbo. It has one turbo on each side of the engine, because the engine is V6, it has two exhaust manifolds. The turbo's come off these. They are not run in sequence (one after the other) they are just off the two different exhaust manifolds.

Nor_Cal_Driver
03-14-2007, 09:59 AM
The 2.7 L engine in the S4 and (some?) A6 is twin-turbo. It has one turbo on each side of the engine, because the engine is V6, it has two exhaust manifolds. The turbo's come off these. They are not run in sequence (one after the other) they are just off the two different exhaust manifolds.


I know that they on opposite cylinder banks, what I want to know is if the come on together or in sequence, one spools low end and the other spools on top end of rpm range.

TQMB5
03-14-2007, 10:15 AM
I know that they on opposite cylinder banks, what I want to know is if the come on together or in sequence, one spools low end and the other spools on top end of rpm range.
i would doubt it since they are both the same sides, meaning they are both going to spool at the same time, so why would one boost before the other?

seank
03-14-2007, 10:34 AM
an S4 spools in parallel, meaning at the same time. not sequential like a twin turbo supra.

jaredpgh
03-14-2007, 10:36 AM
the new bmw 335i has sequential turbos, but it has over 3 liters of displacement to use them with.

rrei
03-14-2007, 01:53 PM
I know that they on opposite cylinder banks, what I want to know is if the come on together or in sequence, one spools low end and the other spools on top end of rpm range.



keep in mind exhaust gases is what spools a turbo so u all exhaust gases exit the manifold at the same time thus spooling the turbos at the same time .

bOOOOstedAudi
03-14-2007, 02:23 PM
the new bmw 335i has sequential turbos, but it has over 3 liters of displacement to use them with.


and 1.8l 4 cyl does not help. i think it would have trouble pushing 2 turbos efficiently.

these go hand in hand

ibew5audi
03-14-2007, 02:23 PM
what about hks's twin charged mr2? I personally like lag.
It had supercharger for low end and turbo for top.

seank
03-14-2007, 02:36 PM
you like lag? please elaborate on why you enjoy this.

mike-2ptzero
03-14-2007, 02:49 PM
what about hks's twin charged mr2? I personally like lag.
It had supercharger for low end and turbo for top.

Just used a turbo to force air into the SC. Not exactly the greatest thing in the world seeing that you are forcing hot charged air into a SC which is then just heating it up even more. Both also run at low boost so just doing a high boost turbo setup makes more power.

ibew5audi
03-14-2007, 02:54 PM
I grew up riding 125's. I don't always need power on tap. Drives like a 4 cyl til you grab a gear (or 2). If lag sucked so bad, I'd buy a v8. People whining about lag are the reason a4's come stock with a k03. (all respect due)

audi_a4_kid
03-14-2007, 03:01 PM
how much smaller fo a turbo then a k03 could you find?

you could take a turbo from a smart car.[wrench]

Nor_Cal_Driver
03-15-2007, 09:55 AM
i would doubt it since they are both the same sides, meaning they are both going to spool at the same time, so why would one boost before the other?

First of all, I really don't know, just trying to learn.

Wouldn't wastegate control allow the ecu to utilize boost from one turbo first and another later?

Militant-Grunt
03-15-2007, 10:18 AM
The new 335i has this setup.

ShawFM
03-15-2007, 11:00 AM
I was reading about turbos -ages- ago(long before I'd even driven a car), probably on wikipedia or howstuffworks or something like that, but I remember that they said a problem with turbo's is turbolag, spool time, etc. We all know this of course, but what was interesting about it was that they said one way car companies attempted to deal with it was by putting a small turbo and a big turbo in series. So the exhaust goes through the small turbo, into the big turbo, and on to the cat or test pipe or whatever. Bonus is, the small turbo spools up right away giving you "instant" power, and then the big turbo spools giving you lots of power.

Soo, do you think it would be possible to do? a k04 and then a BT? Ignore the fact that it probably wouldn't fit for now, what kind of problems do you suppose it might cause? You'd need lots of oil/coolant lines, I suppose... 2 boost controllers? Weird tuning...

Anyway, I'm just throwing it out there.
This is the setup you want, one tiny turbo per cylinder (http://www.gizmag.com/go/5227/), mounted close to the head for virtually no lag. By Owen Developments (http://www.owendevelopments.co.uk/index.asp)

Link to picture (http://www.gizmag.com/go/5227/picture/20323/)

mike-2ptzero
03-15-2007, 11:23 AM
This is the setup you want, one tiny turbo per cylinder (http://www.gizmag.com/go/5227/), mounted close to the head for virtually no lag. By Owen Developments (http://www.owendevelopments.co.uk/index.asp)

Link to picture (http://www.gizmag.com/go/5227/picture/20323/)

Only bad part is getting each turbo to flow the same. Man I though having 1 carb per cylinder on a bike was hard enough to keep tuned 100% correct all the time, that turbo setup looks like a headache waiting to happen.

TQMB5
03-15-2007, 11:31 AM
First of all, I really don't know, just trying to learn.

Wouldn't wastegate control allow the ecu to utilize boost from one turbo first and another later?

yes i suppose they could but do you see why that would not make any sense, if both are ready to make boost, why not utilize it and have a early/bigger power band.

mike-2ptzero
03-15-2007, 11:50 AM
yes i suppose they could but do you see why that would not make any sense, if both are ready to make boost, why not utilize it and have a early/bigger power band.

Plus the fact that if both are the same size they will only produce the same amount of air flow(CFM) at the same rpm so there isn't anything to gain vs just running both of them exactly at the same time. Other problem would be that the first turbo would be pushing air into the turbo on the other side that isn't moving air at the same boost pressure since they are both part of the same IC setup and both feed into the intake manifold thru 1 throttle body.

ShawFM
03-15-2007, 11:56 AM
Only bad part is getting each turbo to flow the same. Man I though having 1 carb per cylinder on a bike was hard enough to keep tuned 100% correct all the time, that turbo setup looks like a headache waiting to happen.

I know what you mean about balancing the carbs. I've been riding bike for over 25 years now. But the turbos wouldn't have to, flow the same. If you look carefully the exhaust mani is tied across the 4 turbos, and a with a common intake the pressure into each cylinder should be the same. The computer can do the rest of the work for fueling, no problem.
But just the thought of having to change an oil line or a middle turbo, uggh.

Nor_Cal_Driver
03-15-2007, 12:01 PM
Plus the fact that if both are the same size they will only produce the same amount of air flow(CFM) at the same rpm so there isn't anything to gain vs just running both of them exactly at the same time. Other problem would be that the first turbo would be pushing air into the turbo on the other side that isn't moving air at the same boost pressure since they are both part of the same IC setup and both feed into the intake manifold thru 1 throttle body.


I see what you mean by not sequencing them. I just thought of that because of how the k03 runs outta breath so early I thought you might be able to save a breath for after 5K rpms, but obviously a BT would be easier, I'm just curious for the sake of conversation.

bass_lover1
03-15-2007, 12:03 PM
If memory serves me correctly, isn't VW already doing something like this? But not with two turbochargers, but rather a supercharger for low RPMs and a turbocharger for higher RPMs? Granted I believe this was done on a 1.3 liter motor so I'm not sure what the performance gains are, but I'm sure it's an interesting ride anyway.

ShawFM
03-15-2007, 12:21 PM
If memory serves me correctly, isn't VW already doing something like this? But not with two turbochargers, but rather a supercharger for low RPMs and a turbocharger for higher RPMs? Granted I believe this was done on a 1.3 liter motor so I'm not sure what the performance gains are, but I'm sure it's an interesting ride anyway.

It is a 1.4l engine (http://www.vwvortex.com/artman/publish/volkswagen_news/printer_1496.shtml). It's on vwvortex.com
http://www.vwvortex.com/artman/uploads/036_001.jpg

JMaxx93
03-15-2007, 02:28 PM
Correct me if I'm wrong. But theres way more difference between parallel and sequential setups besides wastegate action. If i understand correctly, engineering a sequential V configured engine would be a big pain in the ass, as illustrated by my detailed drawings.

http://i156.photobucket.com/albums/t37/jmaxx93/ParallelvsSequential.jpg

Note: for those of you conceptually disabled, I've excluded intake paths and much much more.

ShawFM
03-15-2007, 03:20 PM
Correct me if I'm wrong. But theres way more difference between parallel and sequential setups besides wastegate action. If i understand correctly, engineering a sequential V configured engine would be a big pain in the ass, as illustrated by my detailed drawings.

Note: for those of you conceptually disabled, I've excluded intake paths and much much more.
Not really, it wouldn't be far from the concept of a single turbo on a V engine. They would still end up in a common collector and then the turbo. Such as a Grand National or GNX both had single turbos. With a lot of lag built in.

JMaxx93
03-15-2007, 04:55 PM
both the same engine too, right?

ShawFM
03-16-2007, 04:54 AM
both the same engine too, right?

yup, buick 3800, pontiac did one too (on the TA)

onemoremile
03-16-2007, 05:06 AM
That Trans Am pace car was a strange bird.

The sequential turbos is more of a marketing thing that anything else. It looks good on a brochure and everyone likes to say they have two turbos. In reality, it is a much more complicated system and a vacuum leak is a nightmare. The FD RX7 has what looks like a half mile of vacuum lines. A single turbo rated for the same flow as the pair may actually have a lower boost threshold since there is less mass to get moving.

ShawFM
03-16-2007, 07:58 AM
That Trans Am pace car was a strange bird.

The sequential turbos is more of a marketing thing that anything else. It looks good on a brochure and everyone likes to say they have two turbos. In reality, it is a much more complicated system and a vacuum leak is a nightmare. The FD RX7 has what looks like a half mile of vacuum lines. A single turbo rated for the same flow as the pair may actually have a lower boost threshold since there is less mass to get moving.

The Turbo T/A was a strange bird. My neighbor lost his licence in one of those within months of getting the car(yes new, back in the day). 135mph in a 55mph, drunk. Not a story I would brag about, his wife scowls at him everytime he tells that story.

http://www.gtasourcepage.com/2002TANatsPics/80PaceCarTA.jpg

mike-2ptzero
03-16-2007, 08:07 AM
Not really, it wouldn't be far from the concept of a single turbo on a V engine. They would still end up in a common collector and then the turbo. Such as a Grand National or GNX both had single turbos. With a lot of lag built in.

Also the S Type and T-Type which were also turbo V6.


I didn't know that the "Grand National" wasn't actually a Buick model name but really just a package that you could get on the Regal at that time.


Found this info on a Grand National site.

"The majority of the '82 Turbo Regals are not Grand Nationals and the majority of '82 Grand Nationals are not Turbo Regals."

Don Supreme
03-16-2007, 08:28 AM
I saw one of those turbo trans AMs at a dyno day. It was stock and made a ISH load of torque (350 RWTQ real early), but only around 250 RWHP or so.

As I said it was stock.